1. The problem statement, all variables and given/known data A solid conducting sphere carrying charge q has radius a. It is inside a concentric hollow conducting sphere with inner radius b and outer radius c. The hollow sphere has not net chare. a) Derive expressions for the electric field magnitude in terms of the distance r from the center for the regions r<a, a<r<b, b<r<c, r>c. 2. Relevant equations E = [1/(4*pi*epsilon_0)](q/r^2) 3. The attempt at a solution I've managed to correctly answer the first two parts of the problem, however when it comes to b<r<c and r>c, I do not get the answers I should. Apparently, for b<r<c, E = 0 since a -q cancels the inner +q. Then, for r>c, E = [1/(4*pi*epsilon_0)](q/r^2) since the total charge enclosed is +q again. I think my problem lies in the fact that I don't fully comprehend what a concentric sphere is or how charge distribution on a concentric sphere works. Based on the solution, I feel I should intrepret that the neutral concentric sphere is neutral because it contain an equal number of positive and negative charges that have all collected on opposite surfaces - the negative charges on the inner surface of the concentric sphere (radius b) and the positive charges on its outer surface (radius c.) Otherwise, I don't quite understand how the -q and overall +q come into play... Thank you very much for taking the time to read this!